Fluid pressure distribution system



N N N y N N. 25,1s2 5... lul [Jl A May 28, 1935- v H. l., BONE 2,003,034

FLUID PRESSURE DISTRIBU TTTTTTTT EM im lfm/IL May 2s, 1935.

yH. L. BONE FLUID PRESSURE DISTRIBUTION SYSTEM Filed Oct. 25, 1932 -2 Sheets-Shet 2 Patented May 28, 1935.

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UNITED STATES PATENT oFFlcE, j., i.

2,003,034 v i n FLUID vPRESSURE DISTRIBUTION SYSTEM.

I HerbertL. Bone, Swissvale, Pa., assigner to The Union Switch & Signal Company, Swissvale, Pa., la corporation of "Pennsylvania f n Applications-october 25, 1932', seriarNo. 639,434

' 56 Claims. (014303-20) My invention relatesto fluid pressure distribution systems, and particularly to iluid pressure distribution systems for classication cary retarder yards of the type in which the track Switches and the'car retarders Yare both operated by fluid presi sure.

, Heretofore in car retarder yards` .of the type described, the fluid for operating both the car retarders and the track switches has been supplied from va singledistribution system in which the iluid pressure was Amaintained at the highest pressure necessary to obtain Vthe maximum retarding force which it wasy desired tok have the carretarders exert, and any retarding forces less than the maximum was obtainedby cutting offv the supplyof fluid to the car retarder operating.

motor orv motors bysuitable. valve mechanism when the pressure in the operating vmotor or motors had reached a Value correspondingto the desired retarding force. If rthe pressure-,ofthe fluid in the operating motor or motors increased' above the value necessary to causeY the desired retarding force, the excess fluid was vented to atmosphere. Furthermore, if it'was desiredto reducethepressure of the iiuid inthe operating motor or motors in .order to decrease-the retarding force, or to release the retarder, or for any other reason, all of the fluid in the operating motor or motors was vented to atmosphere.

In accordance with my present invention it is proposed to save fluid pressure by providing two fluid pressure distribution Systems, in oneff of which the iluid will be maintained at the customary' pressure which is usually approximately Y100 pounds per square inch, and in the other of which the fluid will be maintained at a pressure of approximately one-half the customary pressure, or pounds persquare inch. It is further proposed to supply the iluid tothe car retarder operating motor or motors from the low pressure system wheneverA this pressure is high enough to give the desired braking force, and from the high pressure system only after tnepressure in the operating motor or motors has first been built up to approximately the pressure of the .fluid in the low pressure system from the low pressure system and Still higher braking forces are desired., When the pressure in the car retarder'operating motor or motors is to be reduced, the excess pressure will be Vented into the low pressure system if the pressure in the motors then exceeds that of the low pressure system, and uid will be exhausted to atmosphere only when the pressure of the fluid in the operating motor or motors is to be reduced below that of the l-oW pressure system, It is fur-v ther-proposedtooperate the Switchv movements f on theluid'from Vthe, low pressure system, Suitable switch movements recently having been de- Y yelopedfor this'purpose. Y l. AOne of the, principal objects of my invention-is to `provideV control apparatus which will enable the fluidto-be convenientlysupplied to, and ex Y haustedfrom, the car retarder operating motor ormotors in the manner outlined above. n n Other objects of my invention willappear as 'the description proceeds. o In-the accompanying draWingaVFig. 1 is a dialOl grammatic View showing a typical classification a car retarderv yard provided with one formv of V similar pluralityv of classification tracks vl arranged in 25 eight 4groups rOfic-ur tracks each and each corr- `nected by means of a suitable number of lead tracks 2 and `thenecessary track switches-3, with a main track 4 which extends over an incline or hump, this hump not beingshown thedraW- ing because it forms no part oi my present invention. Each ofthe track switches V3 is intended to Ybe operated by a suitable iiuid pressure actuated switch Yoperating mechanism indicated 'dia-y grammatically in the drawing by a circle, and designated by thereference character M. These switch operating mechanisms may be of any suitable type, one type of switch operating mechanism which is suitable lforlthis purpose being shown in Letters Patent of the United States No.

1,202,164, granted to J. P. Coleman on Oct. V'24 19,16, for Railway traino controlling apparatus.

Associated with the main trackA and with each of the lead tracks 2V isrone or more 4car retarders, eachindicated diagrammatically in the drawings by a rectangle with a semicircle at one .side thereof, and each designatedlby the; reference characterwVC. These car retarders may be of kany desired type as long as they are AfluidV pressureY operated, but apparatus embodying my s invention is particularlysuitable for use inconnection` with car retarders of the type whichv is shown in Fig. v2, and which I will now describe.

Referring to Fig. 2, l the car retarder here shown issimilar to that shown and described .in detail copending application nfor Letters A1 and A2 located on opposite sides of one track Patent of the United states, serial No. 516,883,

filed on Feb. 19,1931, for Railway braking ap-Y paratus, and comprises, briefly, two braking bars rail 6 of a stretch of railway track, which track rail, ashere shown, is secured to a rail support .'l

mounted on an adjacent pair Yof the usual cross-k ties 8, only onecrosstie beingL visible in the drawings. Eachof theV braking bars A1 and 'A2 comprises, as usual, a brake beam 9 and a brake kshoe IU.

The -braking bars A1 and A2' are arranged to be moved toward or away' trom the rail 6 through the medium of` a lever Ii which ispivotally vsupported at one end of alpivotipinV I2: carried bythe Y Y braking bars associated with both rails being derail support y'Land alever I3 which isl'pivotally supported intermediate its` ends on thewpivot pin I2.

a groove I3, similar to the Ygroove IIav in the lever II, which groove receives the braking bar A1. The'parts are "so arranged and so propor-` tioned that if the outer or freey endsv of the levers II and I3 are moved apart;v the braking bars will be moved toward therail into theirY effective or braking positions. When the brakingbars occupy their brakmgpositions, the brake shoes I will engage the opposite side faces of a car'wheel traversing'rail 6 and will retard the speed of the car. TheV center of gravity of the lever lI and braking bar A2 is considerablyY to the right of the pivot pinI2 so that this lever will normallytend to rotate in a clockwisedirectionabout the pivot pin. Similarly, the centerV of gravity of the lever I3 and braking bar A2is to the left of pivot pin I2, so that this lever will norrnally'tendVV to rotate in a counterclockwise direction about-the pivot pin. It will vbe apparent, therefore, that when no force is applied to the'free ends of the levers I'I and I 3 to move them apart, the free ends of these levers will move toward eachother, therebymoving the braking bars to their ineffective or nonbraking positions inA which they are illustrated in the drawings. Y

f The levers Il and I3 are movedapartto move the braking bars to their braking` positionsY by means of a'iiuid pressure motorN comprising a 'cylinder I5 containing a reciprocable piston I6 which drives a piston rod I'I. The cylinder I5 is pivotally connected with the free endY of the lever II by means of trunnions I5b formed'on the side of the cylinder and extending through f Y bifurcations lIb formed on theV lever II, while the piston rod I1 is connected at its freeV end with the free end kI3"V of the leverl3 Aby means ofan adjustable eyeboltjl anda pivot pin I9. Fluid pressure imay be' admitted to the cylinder I5 between the upper end of the'cylinder-and the piston IB through an opening 2D which `is.

The lever Il is inclined upwardly andVVV extends awayfrom the rail '6, and'is providedy sitions, they will exert a braking force which is proportional to the pressure of the fluid supplied to the cylinder` to move them there.

It VShould be pointed out that while I have termined by the speed and the weight of the cars tobe retarded, thelengths of the cars, the number of .wheels on the cars, etc. i

As was previously pointed out, it is proposed in accordance with my present invention to supply the iluid forA operating the car retarder motors from bothV a relatively high pressure ,distribution .system and a relatively low pressure distribution system," andto supply the fluid for operating the switch mechanisms vfrom the' low pressure distribution'system only. For this purpose, high pressure fluid is piped to each of the car'retarders by means of suitable piping designated by the reference character 22, andalow pressure fluid is piped to each ofjthe car retarders and to each of the switch movements by suitable piping designated by the reference character 23. In this connection, it is` tok be under,- StOOdftlTlat there willbe reservoirs (not shown) located at each `of the car retarders and switch mechanisms to supplement the volume of the piping; as is customary in pneumatic installations'.

The fluidin thefhigh pressure system may be vmaintaine'd at V,any desired pressure by any suit'- able Ameans forming no part of my invention and therefore not shown Ain the drawing, the only essential requirement being that the pressure of the fluid be high enough to cause the'v car retarders to exert the maximum desiredretarding in the low pressure system will preferably be maintained atfapproximately half of the pressure in the Yhigh pressure system, or between 50 and 60 pounds per square inch, and may be Vsupplied from the high pressure system by. means of suitable reduction valves not shown, or in any other' suitable manner. If desired, a safety valve not shown may be provided-t0 insure that the uid pressure in the low pressure system will not increase above 60 pounds due to fluidwhich is supplied tor this system by exhausting the excess fluidV fromthe 'car retarder operating motors into the system in the manner 'contemplated-by my invention, as will be made clear hereinafter.

The supply of fluid pressure from the low pressure distribution system to the switch operating mechanisms is controlled by suitable valvemechvanisrn of well known construction, forming no part` of my present invention and therefore not shown. The supply of fluid pressure from the highand low pressure systems to the fluid pressure operating motors of each car retarder, however, is controlled by means of suitable control vregion of piston chamber 25a between the pistons apparatus embodying my invention, which apparatus I will now describe. Referring again to Fig. 2, this control apparatus comprises three main air valves I-I, L andl E, two pilot valves F1 and, F2, and two differential pressure valves D1 and D2. i

VThe main air valves H and E are similar, and each comprises a valve body 24 provided with a piston chamber 25 and a valve chamber 26 separated by a partition 2 through which a valve stem 28 is adapted to slide. vThe upper-end of the valve stem 28 is attached to a piston 28 which is reciprocably mounted inthe piston chamber 25,

while the lower end of thevalve stem has iixedy thereto' a poppet valve 3! which is adapted to seat against a valve seat provided in theyalve chamber 25.l -Aspring 3i Visuinterposc-zd between theV poppe't` valve 39 and the `lower end of the valve chamber 2S, andbiasesV the poppetvalVe-to the position in which it engages the associated valve seat. The piston chamber 25 of each valve on the lower side of the associated piston 29 is constantly connected with atmosphere by means of a vport 32, while the Vpiston chamber 25 of the valve H on the upper side of the associated piston is connected witha pipe 33 leadingfto the diierential pressurevalve D1, andthe piston chamber 25 of the valve' Eon-the upper side of the piston 29 is connectedwitha pipe 34 leading to the differential pressure valveD2. The two pipes 33and 34 serve to conduct fluid to the associated valves for operating these valves under certain conditions which will be described hereinafter. When iiuidA is supplied to piston chamber 25 of valve H `through pipe 33 the piston 23 of this valve moves downwardly, in opposition to the bias of the associated spring'i, thus unseating or opening the associated poppet valve 530,

and under these conditions,"the piping 22 ofthe Y ply of fluid pressure to the pipes 35 and 35 :from

the high pressure distribution system is out oi, In similar manner, when uid pressure is supplied to piston chamber 25 of valve E through pipe 34, piston 29 of this valve moves downwardly and unseats the poppet Valve 3Q of this valve, thus connecting the pipe 2I whichvcommunicates with the cylinders I of theoperating motors N of the associated car retarder between the upper end of each cylinder and the associatedpiston I6, with atmosphere through a port 32a, but when the supply of iiuid pressure to the piston chamber of the valve E is cut off; and pipe 34 'is connected with atmospheregspring SI reseats the poppet valve 33, `thus disconnectingthe pipe 2l, and hence the operating motors of the carretarder, from atmosphere. Y f

Valve L is similar Ato the valves H and E with the exception that the piston'ch'amber of this valve, designated 25a in the drawings, is made somewhat longer than the corresponding piston chamber E5 of the valves H and E, and contains, in addition to the piston 29,- an auxiliary piston iii which is attached to the upper end of a piston 29 and 401communicates with a pipe42 leading tothe differential pressure valve D2, while the regionof chamber 252 above piston 40 communithrough pipe 42, piston 29 will be forced down-1 Y Vwardlyandwill unseat the poppet valve of tribution system is connected with the pipes and 2 i, with theV result that fluid is then supplied to the car retarder yoperating motors frornthe low pressure distributionsystem. When the pop-y f y pet valve 39 of valve L is seated, however, as

shownv in the drawing; the piping 23 of the low sure to the car retarder operating motors from the low pressure distribution system is then cut off.

diaphragm chamber 4'I separated from the valve chamber by a partition 48 thro-ugh which. a valve stem-49 is adapted Vto reciprocate.

The differential pressure Valve D1 comprises valve body 38 provided with two valve chambers' 44 and 45 separated by a passageway 4S, and a' pressure distribution system isY disconnected from vthe pipes 3E and2 I, and the supply of fluid pres- The lower end of thevalve stem 49 is fastened to two of the .diaphragm 50 is constantly subjected to the pressure in .the cylinders of the car retarder operating motorssince the pipe '35 constantly communicates with thesecylinders thro-ugh the valve chamber 26 of valve H,`pipe36, the valve chamber 26 of Valve L, andthe pipe 2 I. The portion of thediaphragm chamber 4'! below the diaphragm l'isconnected with therpiping23 of the low pressure distribution system, so that the lower side of the diaphragm 5I. is constantlysubl vjected to the pressure of the iiuid in the low pressure system. As will be seen from an inspection of the drawings, the two diaphragms Eiland 5I are normally bowed upwardly, and the parts 'diaphragms they will move with a snap action,

and will'under no conditions stop in mid stroke. The relative sizes of the two diaphragms 59 and 1 5i aresuchthat the diaphragms will'snap to their' lower positions when the pressure in the retarder cylinders reaches a value slightly below that in the low pressure distribution system.`

It will be apparent, therefore, that y the diaphragms will not snap upwardly to their normal'v Y positions after they have once `been snapped downwardly until the pressure in the retarder v cylinders has been reduced a certain amount below that in theVV low pressure distribution systemi, 4For example, assuming that the pressure inthe lowv pressure distribution system isv 50 fluid in the cylinders of the operatingmotors has been reduced to approximately 40 pounds per squareinch. The upper end of the valve stem,

49 carries two double Vpoppet valves 53 and 54 disposed in the two valve chambers 44 Vand 45, respectively, and, each adapted'to seat against one or the other of two seats provided vin the associ'ated, valve chamber. When the diaphragms 50 and 5| occupytheir upper or normal posi- 'tions as shown, the previously mentioned pipe' 43 is connected with a pipe 55 leading ,from the( pilot valve F1 and the previously mentioned pipe 33 is connected with atmosphere through a port 56. When the diaphragms 50 and 5| aresnapped downwardly, however, the pipe 43 is disconnected from the pipe 55, and is connected with atmosphere through a port 5l, while the pipe 33 is disconnected rom atmosphere and is connected with pipe 55. v Y

The differential pressure Valve D2 is similar in construction to the Valve D1 with the exception that the diaphragme 56 and 5I of this vvalve are normally bowed downwardly and are designed to operateat somewhat diierent pressures from the pressures at which the valve D2'operates, asl

I will explain presently.V The region of diaphragm v chamberk 4l' of this valve below the diaphragm 5| is connected with the pipe 2|, so that the, lower side of the diaphragm 5| isconstantly subjected to the pressure of the Viluid in thecylinders of the car retarder operating motors. The region of diaphragm chamber 4'! abovelthe diaphragm 50 is connected with the piping 23 of the low pressure distribution system by means of avpipe 58,

and it follows that the upper side of the .dia-v phragm 50 is constantly subjected to the pres'- sure in the low pressure distribution system. The

parts are preferably so Yproportioned that whenV the pressure in the cylinders of vthe car retarder operating motors increases to a value which is predetermined ramount above that in the low pressure system, the diaphragms 50 and 5| will snap upwardly, and thatwhen the pressure in the retarder cylinders is subquently decreased to a pressurewhich is slightly more thanthat in the low pressure system, the diaphragms will snap downwardly to the positions in whichthey are shown. After the diaphragms have snapped downwardly they will, of course,remain in their lowermost positions until the pressure in the cylinders of the car retarder operating motors is again increased to a value which is high enough to cause them to again snap upwardly. For example, as-V suming again that the pressure in the low presupper positions until the pressure Yin the cylin-hi ders of 'the operating motors has been decreased to 52 pounds per square inch. Itis, of course, understood that the specific pressures mentioned in describing the operation 0I" the valves D1 and D2 are not necessarily` the exact pressures at which operation of the valves will occur, but are stated for purposes of illustration only. When the di-v aphragms 5|! and 5| of the valveD2 occupytheir lower positions as shown, pipe 34 is connected with a pipe 59 leading to pilotvalve F2 and pipe 42 is Vconnected Vwith atmosphere through the port 51 of valve D2. When thediaphragms 50 and 5| of valve-D2 are snapped upwardly, however, pipe 34 is disconnectedfrom pipe 59 and is connected with ,atmosphere through port 56, while pipe 42 is disconnected from atmosphere and is connected with pipe 59..

The pilot valves F1 and F2 are similar, and each comprises a Valve stem 6D biased to an upper position by means of a spring 6|Y and provided with a winding 62v and an armature 63. When winding 62 of valve F1 is energized'valve stem 6U moves downwardly in opposition to the bias of spring 6|, and under these conditions, the piping 23 of the low pressure system is connected with the .pipe 55, but when Winding 62 of this valve is` deenergizedfvalve stem 6U is moved to its upperposition in` which itis shown inthe drawings, lby means of the spring 6|, and pipe 53 is then disconnected from the piping 2| and is connected with atmosphere through a port 64. Whenwinding 6 2 of valve F2 is energized as shown in thedrawings, valve stem 6|) of this valve is Y,moved downwardly, and pipe 59 is then connected 'with the piping 23 of the low pressure distributionsystem by means of a pipe 65, but when winding G2'ofvalve F2 is deenergized, valve stem 6l) is moved upwardly, thus disconnecting pipe 59 from the piping 23 and connecting pipe 59 with atmosphere through port 64.

.Itrwill be apparent' from thevforegoing, and from an inspection of the drawings, that when winding 62 of valve F1 is energized, so that valve stem 6|! is moved downwardly, fluid pressure from the low pressure distribution system will be supplied to the piston chamber 252 of valve L, or the piston chamber 25 of valve H, according as the diaphragms 5t!` and 5| of valve D1 are then snapped to their upper positions as shown, or are snapped to their lowermost positions, and that the diaphragms 50 and 5| of the Valve D1 will be snapped to their upper or lower positions according as tlie pressure in the cylinders of the car retarder operating motors is ybelow or above Y the limits of operation previously described for this valve. It will also be apparent that when iluid pressure is supplied to piston chamber 25a of valve L, uid pressure from the low'pressure distribution system will be supplied to the cylinders of the operating motors ofthe car retarder, and that whenrluid pressure is supplied to the piston chamber 25 ofvalve H, iiuid pres'- sure from the high pressure distribution system will be supplied to the cylinders of the operating motors of the car retarder. Likewise, when the winding 62 of Valve F2 is energized as shown, so that the'valve stem 60 of this valve is moved to its lowermost position, fluid pressure from the low pressure-distribution system will be supplied to the piston chamber 25 of the valve E, or the piston chamber 252 of the valve L, according as the diaphragms 5@ and 5| of the valve D2 are snapped downwardly as shown, or upwardly, the

vposition ofthe diaphragms 50 and 5i in turn being determined. by the pressure in the cylinders of the car retarder operating motors. It follows thatwhen winding 62 of valve F2 is energized, valve E will open and vent the iiuid from the car retarder operating motors to atmosphere, or valve L will open and exhaust theV fluid from the operating motors into the' low pressure distribution system,according as the pressure of the fluid in the operating motors is aboveor below annessi y the lin'iits.` of'` operation previously vdescribed :for valveD'A.. r n

y The valves F1 and F2 are controlled in part by a'y plurality vofA pressure responsive devices A'each designated lby. the reference character P with a suitable distinguishing exponent. Each of these devices comprises a Bourdon tubevconnected bymeans cfa pipe 4S with pipe 2I., .and subjected tothe pressure in the cylinders of the carv retarder operating motors between the upper ends `of the cylinders and the associated piston',

I6. Each Bourdon tube 66 controlstwocontacts 6'l'-6'la and G'i-lb. The devices P205", 1345*` and Plare so constructed Vthatfthey will operate successively as the pressure in car retarder operating motorsincreases; Forexample, for =all pressures` below 20V pounds per square inch, contact S'I-i-'la of each of these devices is closed. If thev pressurev exceeds 20 pounds per square inch, however, Contact lil-B1L of device Pm-30 opens, and if the pressure exceeds 30 pounds per squareinch, contact 61-611 of device P20-30 closes, In similar mannenthe pressure responsive devices F15-55 'and-'PW-80 are'adjusted to open their contactsy Blf-61a at 45 and '70 pounds per-square inch, respectively, and to close their contacts 61-611 at y55 and 80 pounds'per square inch, respectively. Ofcourse, these speciiic pressures vare not essential," but are only mentionedrfor purposes of explanation. Y The Vvalves Flfand FZare` also controlled by a manually operablecircuit controller G havinga lever 68 movable into engagement with-a se-v lected one of a plurality of fixed contacts 69 to 13, inclusive. 'Ihefcircuitcontroller G will usually be located at a point remote from the braking apparatus, as in a suitable control cabin,vand will be connected with the braking apparatus by means Yofvline wires extending from the-control cabin to the braking apparatus. -Y i As shown'in the drawings, circuit controller G occupies its oli position, so that contact-68-69 is closed.A` A circuit is therefore completed for winding B2 'of valve F2, over which .current flows from a suitable source here shown as a battery J, through contact {S8-B9 of circuit controller Gi, line wire 14, wire 15, winding G2 of valve Fzfwire 16, and line wire 'l1 back to the other terminal of battery J. Valve F2 isltherefore Vener'g'iz'edas shown, so that valve stem S5 of this'valve'occue pies its lowerniost position in which pipe 59 is connected with the low pressure distribution systern. Diaphragms Eiland 5l of valve D2 occupy their lowermost positions, and.- pipe 34 is there# fore connected with pipe 59, and hence with'the iow pressure distribution system', Vwhile pip'ea42 is vented'to atmosphere. `Since'pipe 34 is connected with the low pressure distribution system, iiuidAV pressure from the low pressure distribution sys--A Vtem is supplied' to the piston chamber 25 of -valve sides of diaphragm 5i of valve D2' arefsubjectedV to atmospheric pressure; The'upper side of diaphragm 5D of valve D2, however, isv subjected to the pressure of the Viiuid in the lowpressuredis'- tribution system, and it follows, therefore, that the pressure on the upper side ofthe diaphragm lowermost positions. All 'circuitsforfthe winding=62 of valve F1 are'open, and thiswindingis Y therefore deenergized, so that valve stem 60 occupies its upper position. Pipe 55 is therefore con*-Y fnected with atmosphere through the port 64; 11 The region in diaphragm chamber 41 of differen--rr tial pressure valve D1 above diaphragm 50 is conl- A nected to atmosphere through pipe 135, valve chamber 26 .of valve H, pipe 36, valve chamber 26 of valve'L, pipe '2 i, and port 3221,'While the region.

in valvechamber 51 below. diaphragm 5l is sup-1 piied with iiuid pressure from the low pressureA distribution system. The diaphragms 50-and 5| petgvalve of valve H is held closed byzspring l j 20,v

3|, and the piping of the highv pressure distribution system is therefore disconnected from, the

pipes 35pand 36'.- Furthermore, since pipe 43 is' connected with. atmosphere,A and since'pipe 42 is also connected with atmospherepoppet valve 30 of valve'L is held in its. closed position by spring SLsothat the lowrpressuredistribution system is Vdisconnected from the pipes yt5 and2l.ff The contactsA (i1-#61e of the Bourdon tubes P areall closed,.and the contacts lil- 61h are all open.

will now assume that the operator wishes to cause the car retarder to exert a comparatively light braking force. He therefore moves lever 68 of circuitlcontroller Gfrom the position in which it engages fixed contact 69 to the position in whichitengages xed contact 1U, thus'openingcontact 68--69- and closing contact G8-10; The opening of contact tti- '69 deenergizes valve F2, and valve stem 6D of thisvalve therefore moves to its upper position, thusdisconnectingV pipe from pipe 65,"and connecting pipe 59 with atmosphere. The supply of fluid pressure to pis.-

tonchamber 2,5 of y.valve E is then cut oif, andthe Y Y pistonchamber of this valve is ventedl to atmosphere, so that poppet valve 3i) ofv valve E'jnowk closes; thus'. disconnecting the upper ends of @the cylinders of K theA car' retarder operating'v motors from atmosphere.Y The closing of contact 68-'10 i completes a circuit for winding 62 of valve F1,

and current iiows from battery J through contact (iii-Jil,V line lwire T18', contact B'I--i'la of vpressure responsive Ydevice Pmi-3, Wires 'i9 and 80, winding 62 of'` valve F1, wirefl, andiline wireTLback to battery J '.A The current flowing inlthiscircuit Aenergizesvalveelm, and valve stem 60 therefore moves to its lowermost iposition,` thus supplying j vfluidpressureto piston chamber25a of valveLL `from the low pressure supply, throughvalve F1,

pipe 55, valveD1, and'pipe43. Piston 4U ofV valve L lis therefore Aforced to' its lowermost position;

Vthus'opening poppetvvalve 30 ofy this valve, and henceadrnitting fluid pressure fromrthe low presco'Y sure 'distribution 'system tothe upperV ends:v of

the cylinders of the operating motorsofV the'cai retarder; When the pressure in the cylindersof t Y Y .Y

the operating motors reaches 2 0 pounds persquare vice P2o`30 opens and interrupts the circuitpreviouslyY traced for windingv 62 of valve F1,fthus deenergizing this valve. When -valve F1 becomes' deenergized, thel supply of fluid to pistonl chamber 2,5L of valve L is'cut oiand thepressuie which 'loV waspreviously suppliedfto this piston'chamber is ventedv to atmosphere through pipe 43, valve D1;

pipe 55,valve F1 and port 61|, i'Poppet-valveSO o f valve L- therefore'closes and cutsoff the'supplyofy Y Ybattery J.

fluid pressureto the cylinders ofthe car retarder operating motors. If when contact 68--10 of circuit controller G is closed, the pressure in the car retarder operating motors exceeds 30 pounds per square inch for any reason, contact 61-611 of `pressure responsive device P2040 will become closed, which will close another circuit for winding 62 of vvalve F2, this latter circuit `passing fromy battery J through line wire 18, contact 6T-61b of vpressure responsive device P20-3", wires 82, 83

and 15, winding 62 of valve F2, wire 16 and line.

Wire '11 back tov battery J. rValve F2 will therefore become energized and will cause poppet valve 30 of valve E toopen inthe manner previously described. When poppet valve 38 of valve E opens, fluid pressure is vented to atmosphere from the operating motors through the port 3211, thus causing the pressure in the vmotors to decrease.

As soon as .the pressure decreases below 30 poundsl per square inch, contactY 6'|-E'|b of pressure responsivedevice P230`willagain open, and will deenergize valve F2, thereby. causingpoppetvalve 30 of valveE to again become closed and disconnect the operating motors'from atmosphere. It will be apparent, therefore, thatwhen lever 68 of. circuit controller G occupies the position in which` contact 684-18 is closed, a pressure of between 20 and 30 pounds per square inch will be maintained in the cylinders'of the car retarder operatingY motors.

I will` next assume that it is desired to vcause e thebraking bars to exert a. still higher braking force,4 The operator will therefore move lever 68 of circuit controller G to the position in which contact Sti-1| is closed. Under these conditions,

winding 6210i valveF1 becomes energized over another circuit whichV passes from battery J through contact A 'S8-Hof circuit. controller G,

line wire 84, contact 61-61? of pressure responsive device F15-55, wires 'i9 and 80, winding 62 of valve F1, wire 8|', and line wire backto Since the .diaphragms 50 and 5| of valve Dl still occupy their upper positions, the energization of valve F1 ,causes fluid pressure to be admitted to piston chamber 25'f1 of valve L on the upper side of the piston 4|] in thermanner previously described, and poppet valve. -30 of Vvalve L therefore becomes opened and admits iluid pressure from the low pressure distribution system tothe car retarder operating motors.y

Poppetvalve 30 of Valve L'will now continue to admit uid to the car retarder operating motors from the low pressure distribution system until the pressure in the car retarder operating mc-y tors reaches 45 Ypoundsfpe'r square inch at which contact 61-6e-of pressure responsive device F15-55 will open and will deenergize'.l jvalve F1. When this happens, poppet valve 30 of valve L will Vagain become closed in `the manner pre= viously described, Vthus cutting .offYV the'supply of uid pressure from the low pressure rdistribuv tion system to the car retarder operating motors. Y If the' pressure. in the `car retarder'operatingV motors increases above 48Vpounds per square inch for any reason, the diaphragmsl 50 and 5| of valvefDLwillsnap upwardly, but as long as the' closes andV reenergizes valve' F1, the energization of ,valve F1 will now cause poppet valve 30 of valve H to 'open and admit iiuid pressure to the car retarder operating motors from the high pressure distribution system. It should be pointed out at this'point that, if valve D1 hasV once reversed when contact 68-'|| of circuit controller G isv closed, it will remain in its reverse position as longas contact 68`|| remains closed, since 'the pressure in the operating motors is never permitted to decrease far enough below 45 pounds per square inch to cause the valve vto return to its normalposition, it being remembered that this valve will not return to its normal position. until the pressure in the operating motors decreases to 40 pounds per square inch. If the pressure in the car retarder operating motors exceeds 5,5v pounds per square inch so that contact 61-611 of pressure responsive device 13515- becomes closed, another circuit for winding 62 vof valve F2 will become closed, and current v,willilow from battery J through contact 68-'|| of circuit controller G, line wire 84, contact'6'I-6'Ib of pressure responsive device F15-55, wires 82,83 and 15, winding 62 of valve F2, wire '16,Y and line wireV back to battery J. VValve F2 will thereforebecome energized. When this happens, if the pressure in the car retarder operating motors does not exceed pounds per square inch as will usually be the case, so that therdiaphragms of valve D2 still occupy their lower or normal positions, fluid pressure will be Vadmitted to the piston chamber 25 of valve E in the manner previously described. Poppet Valve 30 of valve E will therefore become opened, and

rwill exhaust fluid from the car retarder operating motors to atmosphere until the pressure in the motors decreases sufliciently to cause contact 6.'|-6'|1J of pressure responsive device F15-55 to open and deenergize winding 62 of valve F2. If,

however, when contact (il-6la of pressure responsive device P25-.55 becomes closed and completes the circuitl just traced for winding 62 of Valve F2, the pressure in the car retarder operating motors should increaseL to 60 pounds per square inch, so that the diaphragms of valve D2 aremoved upwardly, fluid pressure, instead of being admitted to piston chamber 25 of valve E, would be admitted to piston'chamber 25a of valve L between the Ypistons 4|! yand 29, and poppet valve 36 of Valve L would therefore open. Under these conditions, thejexcess fluid would be vented into the VVlow pressure distribution system until the pressure in the operating motors had decreased suiiciently to cause contact 61-61bof pressure responsivegdevice P45-55 to open and deenergize valve F2. It will be seen, therefore, that when contact 68'|| of lever L is closed, the pressure in the car retarder operating motors uwill be maintained at a pressure oivbetween 45 and 55 pounds per square inch.

wire'|| back to battery J. If when windingY 62` of valve F1 becomes energized, the diaphragms 5|] and 5| of valve D1 still occupy their upper or normal positions, fluid pressure Awill be admitted to piston lchamber 25a of valve L, and

poppetvalve 35i of Vthis valve will therefore become opened, and will admit fluid pressureto pressure in the low Vpressure distribution system f reaches 48 pounds per square inch, at which time, the diaphragme 5B and 5I of valve D1` will move to their lowermost positions, thus cutting oifthe supplyof fluidr pressure to piston chamber it of valve L, and causing fluid pressure to be supplied to piston chamber 25'of valve H. Poppet valveSof valve L willthereforebecome closed, and poppet valve of valve H willv become opened. The closing of poppet valve 3U of valve L will cut oi the supply ofA iluid pressure Yfrom thelow pressure distribution system to the car retarderoperating motors, while the opening of poppet valve Se of valve I-Iwill cause fluid from the high pressure distribution system to be sup-r plied to the car retarder operating motors.. If whenwinding 52 of valve F1 becomeslenergized,

the diaphragms 5i) and, 5i of, valve D1, Vinstead of occupying their upper or normal positions asY just described, hadr been. previously moved to their lower positions, iiuidl pressure from the low pressure system would have been'supplied toipiston chamber 25 of valve YI-I immediately, thus Acausing fluid from the highpressure distribution. 'systemto be initially supplied tothe car retarder motors. -After poppet valve 3)` of.Y valvev H has once become opened, it will remaink open until.

the pressure in the Voperating motors exceeds'ZO pounds per square inch, at which -time contact responsive device Flo-8 Y will become opened, thus deenergizing winding 62 of valve F1, andhence causing poppet valve ofvalve H to become closed and cut off the supply of iuid pressure to the car retarder operating motors.- I the pressure in the car retarder operating motors now increases to 80 poundsper square inch for anyv reason, so that contact ell-Sib of pressure responsive device Ffm-Sober' comes closed, winding B2 ofvalve E2 will become energized over stillanothercircuit which j passes from battery J .through contact B8-'12 of circuit controller G, line ,wire 85contact GTI-51h of pressure responsive device 'PW-3,

- wires 83'andl5, `winding 62 of valve F?, wire 16,

and linejwire 'il back to battery J. l When winding, t2 of valve F2 becomes energized underA these conditions, the valve stem V49 of differential pressure valve D2 will occupy its upper position, and

Y to

iiuidpressure will therefore be suppliedY topiston chamber 25a of valveL between the pistons 4D and 29, thus causing poppet valve 30 `of valve L to become Vopened.- When poppet valve 30 ofv valve AL becomes opened, fluid pressure will lbe Vented from the car retarder operating motors into the low pressure distribution system. P oppet valve 30 of valve L will remain open until the pressure inthe operating motors decreases below 80 pounds per square inch at whichtimecontaot` when contact 694-'32 of Acircuit controller G is closed, iiui'd pressure will be supplied to the car retarder operating motors at a pressure rof be` vtween 70 and 8O pounds per square inch.

Ir the operator desires to cause the car retarder to exert its maximum; braking force, hewill move lever 68 to the position'` in Whichcontact Ilili-13 is closedn. Under these conditions,` winding 62 of valve F1 will become energized and will constantly remain energizedby virtue of a circuit lwhich passes from battery J lthrough contact GBS-'13 of circuit controller G, line wire $36, winding 62 of valve F1, wire Bi, and line Wire 'll back to battery J. When valve 'Flbecomes energized, ,if Valve D1 occupies, the position shown, valveL will initially become operated, and' will admit fluid pressure to the car retarder operating motors from the low pressure distribution system until the; pressure in the operating motors builds up to vi8 pounds Apersquare'inch,at which time diaphragme 5i? and 5| of valve Dl will move down- 4wardly, thus causing poppetvalve 3c V of valve L to'clo'seand poppet valve 3@` of valve Htc open.` VAssoon aspoppetvalve jof valveL closes,the

supply of Huid pressure to the car Vretarderopsystem Willthen be cut/rolf, and when poppet valve 3l! of valve H closes, iluid pressure will then be supplied to the operating motors from the high pressuredistribution system. -If when valve F1 becomes energized, valve D? instead of occupying its normal'position, occupies its reverse position,

position in which contact 68-'13 is closed, the

pressure in the'icar retarder operating motors will build up to the pressure of the high pressure distribution system. I

llt` should be observed that if the operator moves Y,

` 25' poppet valvef@ of valve H will immediately open, j and will supply fluid pressure to thecar retarder 4operating motors Afrom the high pressuredistri-l y 'bution system'g-V'It will be seen, therefore, that Vv'fhen'lei/,er Y$8 of circuiteontroller G' occupies Vthe v30 lever SS cf circuit controller G from a position correspondinggtoa higher braking force to a position corresponding to alower braking force, the rapparatus will immediately and automati cally reduce the braking pressure to the ,value tion of thedrawings without tracing thesequence ofpperation in, detail. i f

,In'ordertof restore the car retarder to its open corresponding to the new position of the levern Y yal mannerV which it is believed will be readily unyderstood from the' foregoing and from aninspe'cor ineffective position, vthe operator moves lever 63er circuit controller G to the 'position-in which it is illustrated in the drawings. Under these conf ditions, if valve F1 is energized, it will become deenergized and, valve F2 will becomeenergized over the `circuit Ypreviously traced including v,Contact 6S-6 of leverL. When valve :F2 becomes ener-' gized, if the pressure in the car retarder operating rnctorsis above 60 pounds per square-inch, so that the diapliragms of valve D2 occupy their upper positions, fluid pressure will be supplied to pistonA chamber 25a of valve L betweenlthe pistons 29 and 49, thus causing poppetv valve S of valve L to open. When valve 3Q opens, since the pressure of their lowermost position, thus cutting 0E the supplyvof iiuid pressure to the piston chamber 2,5at

ofy valve lL between the pistons 2S and sie, and

ventingthisregion ofl the piston cliamberle to atmosphere.

Poppet valve 3i),` o'valve'Ld'willv therefore now becomeclosedand willdisconnect j the operating 'motors from the low pressure dis- ,Y

tributionsystem. The movement of'diaplhragms eiland 5I of ValveD to their lowermostpositions system embodying my invention is that it willv materially reduce the amount of fluid required for the operation of a car retarderiyard by reason of 'the conservation of fluid which Awould otherwise be exhausted to atmosphere. This conservedrfluid is. returned to the low pressure system-fromwhich it is used for both the car retarders and the switch movements f Y' l,

Another advantage of a fluid pressure distribu- Vtion system embodying my invention is that Ysince the fluid pressure in the low pressure distribution system ydoes not have tobe compressed to a pressure as high as is necessary when iluidat only one pressure is provided for operating bothr car retarders and the switch movements, less energy is required to operate the compressors.

'Although I haveV herein shown and described i only one form of fluid pressure "distributionsys-v tems embodying my invention, itY isV understood that-various changes and modifications may be made therein Within .the scope of the'appended claims Without Ydeparting from Ythe spirit and scope of my invention.

- Having thus described my invention, What I 1. In combination, a fluid pressure operated device, a first pipe in which fluid is maintained at a relatively low substantially constant pressure, a second pipe in which fluid `is maintained at a relatively high substantially constant pressure, means for at times supplying fluid to said device from said rst pipe and for at other times supply- `ing fluid to said device from said second pipe, and

means for at still other times exhausting fluid from said device into said first pipe or to atmosphere'according as the pressure of the fluid in the device `is above or below a predetermined pressure which is somewhat higher than the pressure 'of the fluid in said first pipe.

2. In combination, a fluid pressure operated device, a first pipe in which fluid is maintained at a' relatively low substantially constant pressure, a second pipe in, Which'fluid is maintained at a relatively' high substantially Yconstant pressure, means for at'times supplying fluid to said device from said first pipeY and for at other times supplying fluid to said device from said second pipefand means controlled by the pressureV of the fluid Ain said device for at still other times automatically exhausting-fluid from the device into said-'first pipe or toatmosphere according as`A the pressure of the fluid'in said device is above or below a predetermined pressure Which is substantially equal to the pressure of the fluid in said iirst'pipe.

3. In combination, a fluid pressure operated'device, a first pipe in Which-fluid is maintained at a relatively low substantially constant pressure, a second pipe in which iluid is maintained at a relatively high substantially` constant pressure,`

means for at timesA supplying fluid to said device from said first pipey and for at other times supply- Ving fluid to said device from said second pipe, and means eective when the pressure of the fluid `in said. devine isabnve the pressure of the L:fluid in said rst pipe for at stillother times exhausting fluid from the device into said rst pipe until thepressure'in the device has decreased substantially to thepressure .of fluid in said first pipe and for subsequently venting the fluid from the device to atmosphere.

V4. In combination, a uid pressure operated device, a first pipe in which fluid is maintained at a relatively low substantially constant pressure, a lsecond pipe in which fluid is maintained at a relatively g high .substantially constant pressure, means for at times supplying iluid to said device from said iirst pipe and for at other times supplying fluid to said device from said second pipe, and manually controlled means effective when the pressure of the. fluid in said device is above theV pressure of the fluidin said first pipe for at times exhaustingiluid from the device into said rst pipe until the pressure of the fluid in the device has decreased substantially to the pressure of the fluid in said first pipe and for subsequently f automatically venting the fluid from the device to atmosphere. Y

5.7In combination, a fluid pressure operated device, a first pipe in Which fluid is maintained at a relatively low substantially constant pressure,Y a second pipe in which fluid is maintained at a relatively high substantially constant pressure, means forat times supplying fluidto said device from said first pipe and for at other times-supplying fluidto said device from said secondV pipe, means at Vtimes effective when the pressure of the fluid in said device is above the ,c pressurev of the fluid-in saidrst pipe for venting thefluid from said device into said rst pipe untilV the pressure of the iluid in the device decreases substantially to the pressure of the fluid in the first pipe, and other means at times effective when the pressure of the uid in said device is substantiallyv equal to or less than the pressure in said first pipe for venting the fluid from said device to atmosphere.

6. lncombination, a fluid pressure operated device, a first pipe in which fluid is maintained at Y a relatively 10W substantially constant pressure and a second pipe in which fluid is maintained at arelatively high substantially constant pressure, means for supplying fluid to said device from said first kpipe until the pressure of the fluid in said device builds up to substantially the pressure of the liluid in said first pipe and for subsequently automatically supplying fluid to said device from said second pipe, and means at times effective for exhaustingfluidV from said device into said first pipe or to atmosphere according as the pressure ofr the fluid inV theY device is above-or below a predetermined pressure whichv is only a little higher th'an'the pressure of the fluidin said rst pipe,

f'l. In combination, a fluid pressure operated device, a first pipe in which fluid is maintained at a -relatively low substantially constant pressure and a secon-d pipe in Which fluid is maintained at a' relatively highsubstantially constant pressure, means` for supplying fluid to said device from said first pipe until the fluid in said device builds up to substantially the pressure of the'fluid in said first pipe and for subsequently automatically tc substantially the pressure of the fluid in said.`

venting fluid fromV said device to atmosphere.

8.--In`combination, a fluid pressure `operated first vpipe and for subsequently automatically a first valve for admitting fluid from said'loW` device, a first pipe in which fluidisV maintained at a relatively low substantially constant pressure and a second pipe in which fluid is maintainedat a relatively high substantially constant pressure, means for supplying fluid to said device from said first pipe until the pressure in the device builds up to substantially the pressure of the fluid in said first pipe, means for subsequently supplying fluid to said device from said second pipe, means effective at times when the pressure of the fluid in said device is above the pressure of the fluid in said first pipe for venting the fluid from said device into said rst pipe, and other' means effective at times vwhen the fluid in said device is substantially equal to or less than the pressure of the fluid in said first pipe for at times venting the fluid from said device to atmosphere.

9. In combination, a fluid pressure motor device, a source of relatively low pressure fluid of substantially constant value, a source of relatively high pressure fluid of substantially constant value, and means for admitting fluid from said low pressure source to said motor device until the pressure in the motor device builds up to approximately the pressure of said low pressure source and for subsequently -admitting fluid from said high pressure source to said motor device.

10. In combination, a uid pressure motor device, a source of relatively low pressure fluid of substantially constant value, a source of relatively high pressure fluid of' substantially constant value, and means for admitting fluid from said low pressure source to said motor device until the pressure in the motor device builds up to approximately the pressure of said low pressure source and for subsequently automatically admitting fluid from said high pressure source to said motor device.

11. In combination, a fluid pressure motor, a

rst pipe'inwhich fluid is maintained at a relatively low substantially constant pressure, a

,second pipe in which. fluid is maintained at a relatively high substantially constant pressure, a first valve for connecting said motor with said first pipe, a secondvalve forr connecting said motor withV said second pipe, a third valve for connecting said motor with atmosphere, and means for selectively operating said three valves.

12;` In combination, a fluid pressure motor, a first pipe in which fluid isrmaintained at a relatively loW substantially constant pressure, a second pipe in which fluid is maintained at a relatively high substantially constant pressure, means for at times supplying said motor with fluid from said second pipe, a first valve for connecting said fluid pressure motor with said flrst pipe, a second valve for connecting said motor with atmosphere, and means for selectivelyoperating said valves in accordance with the pressure of the fluid in said motor;

13. In combination, a fluid pressure motor, a source of relatively high pressure fluid, aL source of relatively low pressure fluid, a first valve for connecting said motor with said low pressure source, a second valve' for connecting said motor with said high pressure source, Yand means for operating said first or said second valve according as the pressure of the fluid in said motor is below j or above a predetermined pressure which is subsource of relatively high pressure fluid ofsubstantially constant value, a source ofrelatlvely low pressure fluid of substantially constantV value.

pressure source to said motor, asecond vvalve for admitting fluid from said high pressure source to said motor, and Ameans for at times operating said two'valves in such manner'that fluid from 4 saidl low pressure source Willbe admitted to said motor until the pressure in the motor builds up to substantially the pressure of .said low pressure source after which fluid from said high pressure source. Will be lautomati'cally .admitted to said motor.V f f f 15. In combination, Va fluid pressure motor, a first pipe connected with a source of relatively low pressure fluid and a second pipe connected With a source of relatively high pressure fluid, a first valve for connecting said motor with said second pipe, a second valve for connecting said motor with said first pipe, a third valve for corrnecting said motor with atmosphere, means Vfor at times selectively operating said first and second valves in accordancewith the pressure of the fluid in said motorY for supplying fluid to said motor, and means for at other times selectively operating said second yand third valves in accordance with the pressure of the fluid in said motor for exhausting fluid from said motor.V

16. In combination, a fluid pressure motor, a first pipe in which fluid is maintained at a relatively ioW substantially constant pressure, a second pipe in which fluid is maintained at a relatively high substantially constant pressure, a first valve for connecting said motor With said first pipe, a second VValve for connecting said motor with said second pipe, a-third valve for connecting 1 said motor with atmosphere, and means 'controlled in part byfthelpressure of the fluid -in said motor for selectively operating said three valves.

17. In combination, a fluid pressure motor, a first pipe connected Witha source of relatively low pressure fluid, a second pipe connected with a source of relatively highpressure fluid, means for at times supplying fluid from said second pipe to said motor, a first valve for Vconnecting said motor with said first pipe, a second valve for connecting'said motor with atmosphere, a third valve responsive to the pressure of the fluid in said motor, and means controlled in partbysaid third valve'for controlling said first and second valves. 1

18. In combination, a fluid pressure motor, a vfirst pipe in which fluid is maintained at a relatively low` substantially constant pressure, a second pipe in Which fluid is maintainedV at a relatively high substantially constant pressure, means forat times supplying fluid from said second pipe to said motor, and means for at other times exhausting fluid from said motor to said first pipe or to atmosphere according as the pressure of the fluid in the motor is above or below a pres-V sure which issubstantially equal. tothe pressur of the fluid in said ilrstpipe. 1 19. In combination, a fluid pressure motor, rfirst' pipe in which fluid is maintainedv at a relatively low substantially constant pressure, a second pipe in which fluid ismaintained at a relatively high substantially constant pressure, means for at times supplying fluidfrom said second pipe to said motor, and means for at other times exhausting fluid from said motor to saidrst pipe until the pressure of` the fluid in the motor decreases tol substantially the pressure of the fluid in said4 rst pipe and for subsequently automatically venting fluidfrom said motor to atmosphere. 20. In combination, a fluid pressure motor, la first pipe connected with ay source of relatively low pressure fluid, a second pipe 'connected with asource of relatively high pressure iiuid, a first :valve forvconnecting said motor with Vsaid first vpipea second valve kfor, connecting said'motor `with said second pipe, a thirdvalve. responsive to the pressure lof the fluid in said motor yand having a valve element which is moved 'toV one position or another positionk according as the pressure of the uid in said motor increases above one predetermined pressure or decreases below e :first pipe connected with a source of relatively another predeterminedpressure which-,is somewhat less than said one'predetermined pressure, and manually controlled means for operating said Second valve or said first valve according as the valve element of said thirdvalve occupies said one position orv said other position. l A

.21. In combination, a fiuid vpressure motor, a first pipe connected with va source of relatively low pressure fluid, ,a second pipe connected with a source of relatively high pressure `iiuid, a rst valve for connecting said motor with said rst pipe, a second valve for connecting said motor with saidrsecond pipe, athird valve responsive tothe pressure of the fluid'in said motor and having a valve element which is moved to o ne position orv another positionaccording as the pressure of the fluid in said motor increases above Vone predetermined pressure which is a little below the pressure of the fluidV in said first. pipe or decreases below another pressure which is somewhat less than the pressure oi the fluid in said first pipe, and manually controlled means for operating said second valve or said first valve according as said valve element occupies said one position or said other position.

22. In combination, a fluid pressure motor, a source of relatively high pressure fluid, a source ,of relatively low pressure fluid,.a first fluid pressure operated valve for connecting said motor with said low pressure source, a second iiuid pressure operated valve for connecting said motor with said high pressure source, a magnet valve, means for at times energizing said magnet valve, yand means effective when said magnet valve. is ,energized for admitting fluid pressure from oneA of Asaid sources to said first or said second fluid pressure operated valve according as the pressure of the fiuid in Vsaid motor is thenbelow or above a predetermined pressure. I

l23. In combination, a fluid pressure motor, a first pipe connected with av source of relatively low pressure liuid, a second pipe connected with a source of relatively high pressure fluid, a first fluid pressure operated'valve for Connecting*- said motor with said flrstpipe, a second fluid pressure operated valve for connecting said motor lwith said second pipe, ar magnet valve, means `for at times energizing said magnet valve, and meanseiiective when said magnet valve is energized forl admitting iiuid pressure from one of said pipes to said first fiuid pressure operated Valve until the fluid in said Vmotor builds up to substantially the pressure ofthe fluid in said first pipe and for subsequently admitting uid pressure to said second fluid pressure operated valve.

"24; In combination, a fluid pressure motor, a l first pipel connected Ywith a source of relatively` creases; a `plurality of circuitsffor said magnet valve eachyincluding a different one of said contacts, and means effective when said magnet valve is energized for admitting fluid pressure from oneof said pipes to -said firstor said second fiuidk pressure operated valve according as the pressure `of the, fluidin said motor is then below or above a predetermined pressure.

25.`Incombination, a fiuid pressure motor, ,a

low pressure fluid, a secondpipe connected with a sourceA of relatively high pressure fiuid, a first iiuid pressure operated Valve `for connecting said motor with said first pipe, asecond fluid pressure operated valve for connecting said motor with said second pipe, a magnet valve, a plurality of contacts, means for successively operating said contacts as the pressure in said motor increases, manually controlled means for energizing said valve over a selected one of said convrwith said low` pressure source, a second fluid pressure operated valve for connecting said mo- 'tor with said high pressure source, a magnet valve, a pluralityV of contacts, means for successivelyoperating lsaid contacts as the pressure in said motor increases, a circuit controllerV provided With a contact-,arm adapted to selectively engage ka plurality of fixed contacts, a plurality of circuits for said magnet valve each including a f different 'one of the contacts of said circuit controller and a different one of said plurality of pressure responsive contacts in series, and means effective when said magnet vvalve is energized for admitting fluid 4pressure from one of said sources to said iirst or said second iiuid pressure operated valve according as the pressure of the iiuid :in said motor is then below or above a predetermined pressure.

27. In combination, a. fluid pressure motor, a

lsource rof `relatively high pressure fluid, a source of relatively lowpressure fluid, a irst fluid pressure operated valve for connecting said motor With said low pressure source, a secondeiiuid pressure operated valve lfor connecting said motor with said high pressure source, a magnet valve, means for at times energizing said magnet valve, means effective when said magnet valve is energized for `admitting fluid pressure from one of said sources to said iirst or said second fiuid pressure operated valve according as the pressure of the fiuid in said motor is then below or above a predetermined pressure, and meanseffective when the pressure in said motor Yhas increased to a predetermined pressure for automatically deenergizing said magnet valve.

Y 28. In combination, a fluid pressure motor, a source of relatively high pressure fluid, a source of relatively low pressure uid, a first iiuid pres- ,.sure operated valve for connecting said motor with said low pressure source, a second fiuid pressure operated valve for` connecting said motor with said high pressure source, a magnet valve, means for attimes energizing` said magnet valve,

'means effective when said magnet valve is energized for admitting fluid pressure from one of `said sources to said first or said second iiuid presone or its other position. v

sure operated valve according as' the pressure of the fluid in said motor is then below or above a predetermined pressure, and means effective when the pressure of the fluid in ksaid motor has increased to a predetermined pressure for automatically deenergizing said magnet valve and for subsequently reenergizing said valve if the pressure subsequently decreases below said predetermined pressurejV Y 29. In combination, ariiuid pressure motor, a source of relatively high pressure fluid, a source of relatively low pressure fluid, a lirst fluid pressure responsvevalve'for'connecting said motor with saidv high pressure source, a second iiuid pressure responsive valve for rconnecting said motor with said low pressure source; a differential pressurelvalve comprising a valve bodyprovided with a diaphragm chamber containing two diaphragms, the region of` said chamber between said two diaphragms being connected with atmosphere and the regions on the other sidesof said two diaphragms being connected with said motor and with said lowpressure'source respectively, rand a valve element controlled by said two diaphragms, the parts being so designed and so vproportioned that when the pressure in said motor increases to a first pressure whichis substantially equal to the pressure of said low pressure source said diaphragms will move said valve element from one position to another position and will subsequently hold said valve element in such other positionl until the pressure of the fluid in said motor subsequently decreases to a second pressure which is somewhat below said first pressure, and means for supplying fluid pressure from one of said sources to said second valve or said first valve according as the valve element of said differential pressure valve occupies its'one or its other position.

30. In combination, afluid pressure motor, a source of relatively high pressure fluid, a source of relatively low pressure fluid, a first uid pressure responsive valve for connecting said motor with said high pressure source, a second fluid pressure responsive valve for connecting said motor with said low pressure source, a differential pressure valve comprising a valve body provided with a diaphragm chamberv containing two'diaphragms, the region of said chamber between said two diaphragms being connected with atmosphere and the regions on the other sides'of said two diaphragms being connected with said motor and with said low pressure source respectively, and a valve element controlled by said two dia- `phragms, the, parts being so designed and so proportioned that when the pressure in said motor increasesto a first pressure which is substantially equal to the pressure of said low pressure-source said diaphragms will move said valve element from one position to another position with a snap action and will subsequently hold said valve element in such other position until the pressure of the fluid in said motor subsequently decreases to a second pressure which is somewhat below said first pressure, a manually controlled magnet valve, and means effective when said magnet valve is energized for supplying fluid pressure from one of said sources to said secondvalve or said first valve according as the valve element of said differential pressure valve occupies its 3l. Incomloination,Y a fluid pressure motor, a source oi relatively high' pressure fluid, a source of relatively low pressure fluid, a first fluid pressure responsive valvefor connecting said motor with said high pressure source, asecond fluid pressure responsive valve for connecting. said motor with said low pressure source; a differential pressurevalve comprising a valve body provided with a diaphragm chamber containing 'two diaphragms, the region of said chamber between said two diaphragms being connected with .atmosphere and the regions on the other sidesof said two diaphragms being connected withV said motor and with said low pressure source respectively, and a valve lelement controlled yby said two diaphragms, the parts being so designed and -so proportioned that when the Apressurein said motor increases to a first pressure .which is rsubi stantially equal to the pressure of said low pressure source said diaphragms will move said valve element from one position to another position with a snap action and will' subsequently hold said valve element in saidother position until the pressure of the fluid, in said motor subsequently decreases to a second pressure which is somewhat below said first pressure; a magnetvalve, a plurality of contacts, means for successively operat- Y ing said contacts as the pressure ofthe fluid in said motor increases, means forenergizlng said magnet valve over a selected one of said contacts, and means effective when said magnet valve is energized for supplying Yfluid pressure from one of said sources to said second valve or to vsaid rst valve according as the valve Velement of said differential pressure valve occupies its one or its other position. Y, y v y 32. In combination, a fluid pressure motor, Ua first pipeconnected with a source of relatively low pressurefluid, a second pipe connected with a f source of relatively high pressure fluid, meansfor at times supplying said motor with fluid from said second pipe, a first valve for connecting Vsaid motor with said rst pipe, a second valve for connecting said motor with atmosphere, a third valve responsive to the pressure of the fluid in said motor and having a valve element which, moves `from a iirstpcsition tofa secondnpositionwhen the pressure of the fluid in said motor increases to a lpressure which. is a'predetermined amount above `the pressure of the lowgpressure system` and subsequently `remains in said secondposi- `,tion until the pressure in the motor subsequently motorwith said first pipe, a second valveffor connecting said motor with atmosphere, a third valve responsive to thepressureof the fluid ein said motor and having a valvev element which ask moves from a lirst position torasecond position when the pressure of the fluid in said motor increases to a pressure which is a predetermined amount above the pressure of the-low pressure system and subsequently remains in said second vposition until the Ypressure in the ,motorv subsequently decreases to substantially the pressure of- 'valve element of said third valve occupies Vits said'motor and having a valve element which moves from a first vposition to asecorid position when the pressure of the fiuid in said motor increases to a pressure which is a predetermined amount above the pressure of the low pressure system and subsequently remainsrin said second position until the'pressure of the Vfluid in the motor decreases to substantially the pressure of the lowrpressure system, a magnet valve, means for energizing said magnet valve, and means effective when Said magnet valve is energized for admitting fluid pressure from one of said pipes to said rst or said second valve according as the valve element of said third valve then'occupies its second oriits first position.

35. In combination, a iiuid pressure motor, a first pipe connected with a source of relatively Vlow pressure fiuid, a secondY pipe 'connected with a source of relativelyhigh pressure f1uidmeans for at times supplying said motor with fluid from said second pipe, a first fluid pressure operatedv uid in said first pipe said diaphragms will move valve for connecting said motor withv said first pipe, a second fluid pressure operated valve for connecting said motor with atmosphere, a third valve responsive to the pressure of the fluid'in said motor and having a valve element which moves vfrom a rst position to a second position when the pressure of the fiuid in said motor increases to a pressure which is a predetermined amount above the pressure of the low pressure system and subsequently remains in said second position until the pressure of the fiuid in the motor decreases to substantially the pressure of the lowpressure system, a magnet valve, a series of contacts, means for successively operating said contacts as the pressure of the fluid in said motor increases, means for energizing said niagnet valve over a selected one of said contacts, and means effective when said magnet valve'is energized for admitting fluid pressure from one of said pipes to said first .or said second valve according as the valve element of said thirdvalve occupies its second or its first position.

36. In combination, a fiuid pressure motor, a first pipe connected with a source of relatively low pressure fluid, a-second pipe connected with a source of relatively high pressure uid, means for at times supplyingA said motor with fluid from said second pipe, a first fiuid pressure operated valve for connecting said motor with said first pipe, a second f iuid pressure operated valve for connecting said motor with atmosphere; a differential pressurevalve comprising a valve bodyY provided with a diaphragm chamber containing two diaphragms, the region of said chamber between said diaphragm being conriected `with atmosphere and the region on the other sides of said two diaphragms being connected with said motor and'with said first pipe respectively, and a vvalve element controlled by said two diaphragms, the parts being so designed and so proportioned that when the pressure or the fluid in said motor increases to a pressure which is a predetermined amount above the pressure of the fiuid in said first pipe saiddiaphragms will move said valve element from a first position to a second position with a snap action and will subsequently hold said valve element in said second position until therpressure of the fluid. in said motor decreases to substantiallyr the pressure of the fluid in said first pipe; and means for supplying fluid pressure from one of said pipesto said first or said second valve according as ,the valve element of said third valve occupies its second or its first position.

' 37. In combination, a uid pressure motor, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fiuid, means for at times supplying said motor with fluid from said second pipe, a first fiuid pressureY operated valve for connecting said motor with said first pipe, a second fluid pressure operated valve for connecting said motor with atmosphere; a diferential pressure valve comprising a valve body provided kwith a diaphragm chamber containing two diaphragms, the region of said chamber between said diaphragms being connected with atmosphere and the regionori the other sides of said two diaphragms being connected with said motor and with said first pipe respectively, and a valve Velement controlled by said two diaphragms, the parts being so designed and so proportioned that when the pressure of the fluid in said motor increases toa pressure which is a predetermined amount above the pressure of the said valve element from a first position to a second position with a snap action and will subsequently hold said valve element in said-second positionuntil the pressure of the fluid in said motor decreases to substantially the pressure of the fluid in said first pipe; a magnet valve, manually controlled means for energizing said magnetvalve, and means effective when said magnet valve is energizedffor supplying iiuid'pressure from one of said pipes to said first or said second valve according as the valve element of said third valve occupies its secondV or its first position.

38. In combination, a fluid pressure motor, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively high pressure fluid, means vfor at 'times supplying said motor with iiuid from said second pipe, Va first fiuid pressure operated valve for connecting said motor with said first pipe, a second fluid pressure operated Valve for connecting said motor with atmosphere, a differential pressure valve comprising a valve body provided with a diaphragm chamber'containlng two diaphragms, the region of said chamber between s'aid diaphragms being connected with atmosphere and the regions of said chamber on the Vother sides of said two'diaphragms being connected with said motor and with said first pipe respectively, and a valve element controlled by said twoj diaphragms, the parts being so designed and so proportioned that whenthe pressure of the rfiuid in said motor increases to a pressure which is a predetermined amount above the pressure of the fluid in said first pipe said diaphragms will move said valve element from a first position to a second'position with a snap action and will subsequently hold said valve ele- `ment in said second position until the'pressure of the fiuid in said motor decreases to substantially the pressure of the fiuid ins'aid first pipe.

agooaos ay magnet valve, a series offcontacts, meansffor.A successively operating saidfcontactsas the pres-'f sure ofthe fluid in said motor increases,='manual ly controlled means for energizing said magnet valve over a selected. one of saidcontactsand means effective when sai'dmagnet valveivis energized fonsupplying fluid pressure from one of said pipes to said vfirstor said second valve-ac#- a source of relatively high pressure fluida first! fluid pressure operated Valve for connecting said motor With said second pipe, a second fluid pressure operated valve for connecting saidk motorl withr said first pipe, a third fluidpressure operV ated valve for connecting said motor with at-* mosp'here, a fourth yvalve responsive-to thepresfr sure ofthe fluid in said motor and having a valve element which moves'from a yfirst position to'a second positionrvvhen' thepressure of the fluid in said motorV increases -to substantiallyvthe pres-Y sure ofthe fluid infsaid first pipe vand- Which-'subsequentiy remains in its second position until the pressure'fof the fiuid in said'vmotor decreases tov a value which is a predetermined amount vbelow thepressure of the fluid in said first pipe,l a fifth valve responsiveto thepressure of the fiuidinl said .motor` andhaving-a valve element whichl moves from a first positionto a second Vposition Wher'rthe' pressure of the fluid in said-'motor in:-

creases'to a pressurewhich is somevvhathigher than thepressure of the fluid in said first pipe and which valve element subsequentlyv remains',A

valve occupies its second or rst-position'and" vmeansfor'at other times supplying uid-fromone of said pipes to said second or said third valves according asthe valve element of saidffifth valve occupies its second or its first position.

40. In combination, afluid pressure m'otorga firstV pipe connectedv With a source of relatively low `pressure fluid, a second pipe connected lWith a' source of relatively high pressure-fluid, a' first fiuidpressure operated valve for connecting/*said moto-r With said second pipe, a second'iluid pressure operated valve for'vconnecting said motor with said first pipe, a thirdfluid pressureoper-- ated valve for connecting lsaid motonwith atmosphere, a fourth valve responsive to the pres` sure of the fluid in said motor and having a valve element which moves-from a first position to a second position when the 'pressure of the uid in said motor increases to substantially the pressure ofthe uidf'insaid first pipe and Which subsequently remains in its second posielement which moves from a first position to a second position when the pressuregof thefluid'V in said motor increases to a pressure Which is somewhat higher than the pressureV of the fluid in said first pipe and which valve elementsubsequently remains rin its second jposition untilf the pressure` of the fluid in saidL motor: subse-Vv ofthe-fluid in said firstpipe, a first magnet valve,

means effective when said first magnet valveis energized for' supplying fluid from. one of said pipes to said first or said second valve accordingas the valve element of said fourthvalve occupies its second' or first position, a second magnet valve,"rneans effective when said second magnet Vvalve is'zenergized for supplying fluid from one of. -saidipipes to said second or said third valve. according as Vthevalve element of 'said fifth ValVeocCupies .its'lsecond or its 'first position,^. and means for selectively energizing said magnet valves.

041; In' combination, a fluid pressure motor,` a' rst pipe connectedvvith a source of relatively low "pressure, fluid, a second pipe'connected with quently. decreases to Vsubstantially the pressure afsource of relatively high pressure fluid',v a firstlV fluid pressure operated Vvalve for connecting saidv motor'withI said'second pipe, a second fluid pres sure operated valve for connecting .said motor with said first pipe, a third iiuid pressurer -operated valvefor connecting said motor with at mosphere, a vfourth -valve responsivento' the'pressure offtherfiuidlinsaid motor and having a valve',V

element which m'oves'from a firstV position toa second position when the pressure of the uid in'said motor increases to substantially thepressure of the fluid vinsaid first pipe andwhich sub?V sequent/ly remains in its second positionJuntil the pressure of the fluid in said motor decreases.

toa value which is apredetermined amount below the pressure of the fluid in said Vfirst pipe, ka fifth y valve responsive tothe pressure ofi theAflu'idin said ,motori and having a valve'ele'ment whichi moves from a 'first' position to a secondposition creases'tov a pressure Which is' somewhat higher than the pressure o'f the fluidin said! first pip'ei and which valve elementsubsequently remains in its second position until the pressurepf the fluid 4in said motor subsequently decreases'to Ysuicstantially the pressure of said firstrpipeja first' magnet valve, means effective when said first magnet valve is Venergized forA supplyingVK fluid from one of said pipesto said first or said second v valve according as the valve element'of/said fourth valve occupies its second or first position, a second-magnet valve,V means effective Vvvhen said second'magnet valve is energized' forsu'pply# tacts, means for operatingisaidcontactsin succession as the pressure -irrsaid' motor increases,

asecond series of contacts one for eachhcontact` of' the rst series, meansjfon` operating eachcontact ofthe second series when the pressure in said. motor increases to a pressurev which isa little higher than the pressure at `which `the corresponding contact of the first series becomes operated, a plurality offcircuits forsaidfirst'magnetvalve eachincluding a different oneof the contacts of saidfrst series, andi a plurality of circuits for said second'magnet second series'.

42. In combination, a fluid pressure motor,'a7`

filet pipe connected-,With a sourcel of relatively Valve each including va different contactof thev lovv pressurefiuid, a second pipe, connected with a sourceof .relatively highpressurefluicl, affirst fluid pressure' operated -valv'e for connecting said Y motor with said secondY pipe, aA second fluidpressure operatedV valve for connecting said motor' With said first pipe, a third fluid pressure operated valve for connectingsaid 'motor with atmosphere, afourth valve responsive tothe pressure of the fluid in said motor and having a valve element Which moves from a firstvposition to a second position whenthe pressure of the fluid in said motor increases to substantially the pressure of the fluid in said first pipe and which subsequently remains in its second position until Y the pressure of the fluid in said motor decreases to a value which is a predeterminedy amount below the pressure of the fluid in said first pipe, a fifth valve responsive to the pressure ofthe fluid in said motor and'having a valve element which moves from agfirst position to a second position when the pressure of the fluid in said motor increases to a pressure which `is somewhathigher than the pressure of theiluid in said first pipe and which valve elem ent subsequently remains in its second position until the pressure of the fluid in Ysaidjniotor subsequentlydecreasesy to sub-1 stantially the pressure of thev fluid in said first pipe, a first magnet valve, means effective when said first magnet valve is 'energized for supplying fluid from oneV of said pipes to said first orsaid second valve according as theV valve element of said fourth'valve. occupies its second or firstposition, a second magnet valve, means effective when said second magnet valve is energized for supplyingfluid from one of said pipes to said second or lsaid third valve according as the valve element of said fifth'valve occupies its second or its first position, a firstseries of pressure responsive contacts, means for operating said contacts in'succession as the pressure of the fluid in said motor increases, a second series of con-V tacts one for each contact of the first series, means for koperating each contact of the second series when the pressure in said motorincreases to a pressure which is a little higher'than the pressure atwhich the corresponding contact of theA first. series becomesv operated, a manually operable circuit controller having a lever which is adapted to engage a selected one of a plurality of fixed contacts, a plurality of circuits for said first magnet valve each including a different contact of said circuit controller and a differentA one of the contactsof saidfrst series, and a plurality of circuits for said second magnet valveV ,each including a different one of the contacts of .low pressure fluid, 'a second'pipe connected with` a source of relatively high pressure fluid,` a first fluid pressure operated valve for connecting said motor with said second pipe, a second fluid pres-v sure operated valve forV connecting said motor with said first pipe, a third fluid pressure operated valve for connecting said motor with atmosphere, a fourth valve responsive tothe pressure. of thefluid in said motor and having a valve element which moves from a first position to a second position when the pressure of the fluid in said motor increases to substantially the pressure of the fluid in said first pipe and which subsequently remains in its second position until the pressure in said motor decreases to a value which 4is a predeterminedamount belowV the' pressure sure of the fluid Vin lsaid motor increases to a pressure which is somewhat higher than the pressure of the fluid in said first pipe and which valve element subsequently remains in its second position until the pressure of the fluid in said motor subsequently decreases to substantially the pressure of the fluid in said first pipe, a first magnet valve, means effective when said first magnet valve is energized for supplying fluid from one of said sources to said first or said second valve according as the valve element of said fourth valve occupies its second or first position, a second magnet valve,y means effective when said second magnet valve is energized for supplying fluid from one of said sources to said-second or said third valve according as the valve element 0f said fifth valve occupies its second or its first position, a first series of pressure responsive contacts, means for operating said contacts in succession as the pressure in said motorincreases,

having a lever which is adapted to engage a selected one of a plurality of fixed contacts, a

plurality of circuits for said first magnetvalve each including a different contact of said circuit controller and a different one of the contacts of said first series, and a plurality of circuits forsaid second magnet valve eachincluding a different one of the contacts of said second series and the contact of said circuit controller which is included in the circuit for the first magnet valve that the corresponding contact ofthe first series is included in.

44. In combination, a railway braking bar. extending parallel to one railof a stretch of railway track, a fluid' pressure motor operatively con'- nected with said braking. bar for moving said braking bar toward the track rail to a braking position, a vfirst pipe connected with a source' of relatively low pressure fluid and a second pipe connectedjwith a source of relatively high pressure fluid, a first `valve for connecting said motor with said first pipe, a second valve for connecting said motor with said second pipe, a third valve for connecting said motor with atmosphere,

vmeans for selectively operating said first and second valves in accordance with the pressure of the fluid in said motor for supplying fluid tor said motor, and means for selectively operating said second and third valves in accordance with the pressure of the fluid in said motor for exhausting fluid fromsaid motor.

45a The method of controlling a plurality of fluid pressureoperated devices some of which are designed to operate on a variable pressure and the remainder of which are designed to operate on a relatively low pressure, said method consisting in yproviding a. first pipe which is connectedwith a source of relatively 10W pressure fluid and a second pipe which is connected with a source of relatively high pressure fluid, supplying fluid to the devices which are designed to operate on a variable pressure from the first pipe as long as this pressure is high enough and from the second pipe only after the pressure in these devices has first been built up to substantially'the full pressure of the fluid in the first pipe and higher pressures are desired, exhausting Vfluid from the devices which are designed to operate Ona variable pressure into the first pipe aooaosfr on positions in which said device is connectedwith saidfsecondl pipefor--first disconnecting said` device from said second pipe and for subsequently, connecting said devicefirst with said; firstpipe until the pressure of the uid in these devices is reducedsubstantially to that of the fiuid in the first pipe if the pressure in these devices is above that of the uidrin the first pipe when it is ydesired to decrease the pressure in these devices and thereafter exhausting the iiuid from these devices to atmosphere if further reduction is desired, and supplying the iiuid for loperating thevdevices which are designed to operate on a lowr'pressure from the first pipe only. Y

, fio. The method of controlling ka plurality of iuid pressure operated switches and fluid pressure operated carretarders Whichconsists in providing two fluid distribution systems one ofrwhich is connected with Ya source of relatively high pressure iiuidA and the other of which is connected with a source of relatively low pressure iiuid, supplying fluid to the retarder operating 'motors from the lo-W pressure system Whenever this pressure is high enough and Vfrom the high pressure system only after the pressure of the' W which is to be exhausted from the car retarder operating` motors into the low pressure system untilV the pressure in the motors decreases to Y substantially the pressure of the low pressure system if the pressure in the motors is then above that in the low pressure system and to atmosphe're when the pressure of the uid in themotors is below that in the low pressure system,V and supplyingfluid pressure to the switch operating mechanisms from the low pressure system.

47. In combination, a fluid pressure 'operated device, a first pipe in which fluid is maintained at a relatively low substantially constant pressure, a second pipe in which iiuid is maintained at a relatively high substantially constant pressure, means for selectively connecting said device vvith said first pipe or said second pipe to admit fluid to said device, and means effective under certain conditions to connect said device with said first pipe for exhausting at least a portion of the fluid in said device into said iirst pipe.

48. In combination, a iiuid pressure operated device, a rstpipe connected with a source of relatively low pressure iiuid, a second pipe connected with a source of relatively high pressure fiuid, manually controlled means for selectively connecting said device with said iirst or said second pipe to admit uid pressure to said device, and means effective if the pressure in said device exceeds a predetermined value whenk said device is connected with said second pipe for automatically disconnecting said device from said second pipe and for subsequently connecting said device with said rst pipe to exhaust at least a portion ofy the fluid in said device into said rst pipe.

49. In combination, a first pipe connected with a source of relatively low pressure fluid, a second pipe connected with a source of relatively high l pressure iiuid, a fluid pressure operated device,

a circuit controller comprising a lever having an off position and a plurality of on positions, means eiiective when said lever occupies its oit position for connecting said device with atmosphere, means eiective when said lever occupies certain ones of its on positions for connecting said device with said first pipe, means effective when said lever occupies other ones of its on positions for connecting said device with said second pipe, and means effective if said lever is moved to its ofi position from any one of its and` then with atmosphere.

' 50. In combination, a ilrst pipe connected with a source of relatively low pressureiiuid, a'second pipe connectedrwith a source of relativ'elywhigh` phere, means effective when saidleveroccupies'.

certain ones of its ,on, positions for connecting, said devicewith said first pipe,` meansl eifective; when'Y said lever occupies other ones of `its on4 positions. for connecting said-device saidv secondr pipe, and means effectiveif saidlever movedto its oil position from any one oiffits on positions in Whichsaid'device isiconiectedwith said second-pipev for-first'disconnect'ing Vsaid device from said secondl pipe 'and for subsequently connecting, said device With said rstfpipe until the pressure of theiluid in'said' device'decreases substantially to the pressure oflthe fluid in. said' first pipe and then with atmosphere.. f

f 5l.Y In combination, a iirst pipe connected with'l a source of relatively low pressure fiiuid, asecond:

pipe connected with/a source of"relativelyhigh`v4 pressure uid, a fluid pressureoperateddevicepa manually operated circuit'controllercomprising a lever having an off position in which said device is connected with atmosphere, a plurality of on positions in which said device is connected with said first pipe, and a plurality of other ,on positions in which said device is connected' with said second pipe, and means effective if vsaid lever is moved from its oi position past,v the on position in which said device is connected with said first pipe to an ,on position in which saidr a lever having an oi`r"position in which said der j vice is connected with atmosphere, a plurality' of on positions in which said device is connected with said -rst pipe, and a plurality of other on positions in which said device is connected with said second pipe, means eective if said lever is moved from its off position past the, on positions in which saiddevice is connected with said iirst pipe to an on position in which said device is connected with said second pipe for first connecting said device with said first pipe until the pressure of the uid in said device builds up to substantially the pressure of the fluid in said first pipe and for subsequently automatically connecting said device With said second pipe,

and means effective if said lever is moved from an l cn position in which said device is connected with said second pipe to its off position for iirst disconnecting said device from said second pipe and for subsequently connecting said device with said first pipe until the pressure in said device decreases a predetermined amount and then Y With atmosphere.

53. In combination, a rst pipein which iiuid is maintained at airelatively 10W substantially constant pressure, a secondpipe in which fluid is maintained at a relatively high substantially constant pressure, a rst'device Which isV at times supplied with fluid from said second pipe, a second device which is at times supplied'with fluid from said first pipe, and means for at times venting uid fromsaid first device into said first pipe. r

54. In combination, a first pipe in which fluid is maintained at a relatively low substantially constant pressure, a second pipe in which fluid Vis maintained at a relativelyY high substantially constant pressure, a rst device which is at timesY supplied with uid from said first pipe and at other times from said second pipe, a second device Which is at `times supplied with iluid from said rst pipe, and means for at times venting iluid from said first device into said first pipe.

55.7Railway brakingV apparatus comprising a` brakingY bar extending parallel toa track rail, a'

uidpressure motor forl moving said braking bar towardrsaid track rail to a braking position, av

having an oif.'V position in which said motor isr connected with'atmosphere and a plurality of on positions in which said motor is normally connected with one or the other of said sources depending upon the particular position of the lever, and means effective when said lever is moved from its off position to a certain one of its on" positions for first connecting thel motor with the rst-pipe source for a sucient time interval to permit the pressure ofthe fluid in the motor to build up to substantially the pressure of the low pressure source and for subsequently connecting the motor with the second pipe.

56. Railway braking apparatus comprising a braking bar extending parallel to a track rail, a fluid pressure motor for moving said braking bar toward the track rail to a braking position, a iirst pipe connected with a source of relatively low pressure uid, a second pipe connected with a source of relatively high pressure uid; a lever having an off position in which said fluid pressure motor is connected ywith atmosphere, an on position in which said iluid pressure motor is normally connected With said rst pipe, and an on position in which said fluid pressure motor is normally connected with said second pipe, and means controlled by said lever and effective when said lever is moved directly from its off position to the onpositionin which said uid pressure motor is normally connected with said second pipe for initially connecting said motor with said first pipe for a sufficient time interval to permit the pressure of the fluid in the motor to build up to substantially that of the iluid in the first pipe.

HERBERT L. BONE. 

